The invention relates generally to molded window gaskets and to the reaction injection molding of such articles from a multi-constituent material in a mold cavity. More particularly, the invention relates to such gaskets for automotive applications and to equipment and methods of reaction injection molding of such articles, wherein the elastomeric urethane window gaskets are integrally molded and securely bonded onto a window panel of glass or other transparent material and include living hinge members incorporated therein. Reference is made to the related copending applications "Molded Window Gasket Assembly And Apparatus And Method For Making Same", Ser. No. 505,196, filed on June 17, 1983, and "Molded Window Gasket Assembly And Apparatus And Method For Making And Bonding Same", filed of even date herewith, both of which are assigned to the same assignee as the present invention. The disclosures of said related copending applications are hereby incorporated herein by reference.
It has been known in the past to fabricate articles such as modular vehicular window gaskets, having hinge members or portions therein, from materials such as polyvinylchloride (PVC) using conventional compression or injection molding techniques. Some of such window gaskets have been injection molded directly onto the window panel, which is made of glass or other substantially transparent material. The window and gasket assemblies have then been installed in a vehicle or other window frame with adhesives and/or with integrally molded fastener protrusions, as disclosed, for example, in U.S. Pat. No. 4,072,340, and with hinge members therein disclosed in U.S. Pat. No. 4,139,234. It has been found, however, that window panel breakage has been unacceptably high in such prior processes because of the high pressures required in the injection molding processes and because of the hardness and rigidity of the mold structures involved. Additionally, because of the types of materials previously used in molding the gaskets, such as rubber of polyvinylchloride (PVC), it has been found that proper adhesion of such gaskets to metal body panels and to glass window panels has been difficult to attain, thereby resulting in water leaks, wind noise, and other related problems, as well as requiring the use of mechanical fasteners to secure the assemblies to the body panels.
In accordance with the present invention, improved apparatuses and methods of reaction injection molding articles such as vehicular window gasket assemblies are provided in order to overcome the above-discussed disadvantages. Such methods and apparatus allow window gasket assemblies to be reaction injection molded from multi-constituent materials, such as urethane, for example, and to be molded at relatively low pressures and securely bonded directly onto the glass or other transparent window panels.
According to the present invention, such gasket assemblies include at least one movable member and a flexible living hinge web integrally molded therewith in a one-piece structure. The window panel assembly can then be movably mounted in a window opening in a body panel and secured thereto. In one embodiment, the gasket assembly also includes at least one integrally molded fixed gasket member with the hinge web interconnectably extending therebetween. The fixed gasket member is adapted to be bonded and secured directly to the vehicle body with adhesives without the need for mechanical fastener devices, thereby simplifying the installation process and making it better suited for robotic or other automated equipment. Because of the incorporation of the flexible living hinge web integrally molded into the gasket assembly such ease of installation is also attainable in window arrangements such as rear quarter windows and folding convertible top windows, for example, wherein at least one window panel must be pivotaly movable relative to the vehicle body. All or a portion of the preferably urethane gasket can also be coated with a pigmented decorative material in the mold cavity if desired.
The gasket assembly according to the present invention may also be fabricated with a lower cross-sectional profile, thereby providing for an advantageous, aerodynamically smooth fit between the window assembly and the body panel. Such lower profile also requires less offset or other forming of the body panel area surrounding the window opening, thus simplifying the body panel fabrication and increasing the design flexibility for such body panels. Also because in at least some embodiments of the invention the gasket and window assembly is preferably bonded and secured to the body panel substantially continuously around the window opening periphery, the localized stress concentrations caused by spaced, discrete mechanical fasteners are substantially avoided and the bonding and securing forces are more evenly distributed. Such modular window structure, with its strong and preferably continuous, peripheral bond allows the window panel to effectively contribute to the structural integrity of the installation, and also to allow for a reduction in window panel thickness and weight.
The strong and secure bond between the preferably urethane gasket member and the preferably glass window panel is achieved by a novel method whereby the bonding occurs simultaneously with the molding process. Generally speaking the preferred bonding method includes the steps of applying a primer material, by spraying or wiping, to at least the peripheral portions of the window panel, allowing the primer to air dry for a relatively short period of time, and inserting at least the peripheral portions into the mold cavity. A flowable urethane, or urethane-containing, multi-constituent material is then injected or otherwise introduced into the mold cavity where the gasket member is allowed to at least partially cure.
In a preferred embodiment of the present invention, an aftermixer apparatus for use in a reaction injection molding system includes a mixing body having at least one common inlet passageway for receiving a multi-constituent material (preferably urethane) in a pressurized flowable state. The apparatus includes a number of mixing passageways adapted to receive the material from the common inlet passageway and separate it into a corresponding number of material flow streams. A common mixing cavity in fluid communication with the mixing passageways reunites the separated flow streams and conveys the material into a gating device for introduction flow the mold cavity. Adjustment means is provided for selectively altering the size of the common mixing cavity and the size of its inlets in order to selectively alter the back-pressure exerted on the material flowing therethrough. Such adjustment feature allows for the optimization of the back-pressure and thus the intermixing of the constituents of the material for a given flow rate and inlet pressure thereof. Preferably, the mixing passageways each extend along a generally serpentine path including at least one bight portion adapted to cause the material flowing therethrough to substantially reverse its direction of flow in order to increase turbulence and enhance the mixing of the material constituents.
At least a portion of the preferred mold cavity of the reaction injection molding system includes one or more elongated elastomeric members positioned generally adjacent the peripheral edge of the mold cavity for supportingly engaging the mold members and the window panel. The flexible elongated elastomeric members are preferably seated in grooves in one or the other of the mold members and are further adapted to substantially minimize or prevent flashing of the gasket material out of the mold cavity and also serve to accommodate variations in the shape of the window panels.
Additionally objects, advantages and features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings.